Various operating parameters which arise in an internal combustion engine (ICE) such as speed, induction pipe pressure, mass of air sucked into the engine through the induction pipe, and the like, are only quasi-continuous values. Upon detailed examination of such values, it was found that they actually vary in rhythm or synchronism with the strokes of the ICE. Control systems which are to provide control for the engine which are generally appropriate thereto frequently consider an average value of the sensed parameters which corresponds to a median or average of the value with respect to a comparatively long period of time. High-accuracy control systems, however, and particularly control systems which are based on electrically and electronically operating systems, require higher accuracy in sensed parameters. Such systems utilize stored characteristics which, for example, store the relationship of data of various parameters in electronic memories, such as read-only memories (ROMs), to control ignition, fuel injection, and the like. A more accurate system which senses those parameters is thus required.
German Patent Disclosure Document DE-OS No. 30 48 674 describes a measuring system to provide an electrical output signal representative of the mass of air being sucked into the induction pipe to an ICE which has a timing circuit synchronized with crankshaft position of the ICE. The air mass signal is measured at different instants of time which correspond to predetermined angular positions of the crankshaft. The actual quantity of air being introduced to the IEC then is computed by a data processing apparatus from the instantaneous values at the respective measuring instants.
The system is entirely suitable, but requires a highly accurate timing control and provides as an output theoretical measured value. The accuracy is excellent; it is, however, frequently not required to provide such a highly accurate output signal and thus incur the expense of this measuring system.